/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright (c) 2008-2011, Salzburg Research. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * - Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * - Neither the name of the KiWi Project nor the names of its contributors
 * may be used to endorse or promote products derived from this software
 * without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 * Contributor(s):
 * sschaffe
 *
 * File Info:
 * User: sschaffe
 * Date: 2011/01/17
 * Time: 16:08
 *
 * Project: KiWi2, kiwi-core module
 */

package kiwi.core.services.io;

import kiwi.core.api.io.KiWiParser;
import kiwi.core.exception.ParsingException;
import org.codehaus.jackson.map.ObjectMapper;
import org.codehaus.jackson.type.TypeReference;
import org.openrdf.model.Resource;
import org.openrdf.model.Value;
import org.openrdf.model.ValueFactory;
import org.openrdf.model.impl.BNodeImpl;
import org.openrdf.model.impl.LiteralImpl;
import org.openrdf.model.impl.URIImpl;
import org.openrdf.repository.Repository;
import org.openrdf.repository.RepositoryConnection;
import org.openrdf.repository.RepositoryException;
import org.openrdf.repository.sail.SailRepository;
import org.openrdf.sail.memory.MemoryStore;
import org.slf4j.Logger;

import javax.inject.Inject;
import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;
import java.io.StringReader;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Set;

/**
 * A KiWi parser takes as argument input format RDF/JSON like (described in http://n2.talis.com/wiki/RDF_JSON_Specification)
 * and parses it in a Sesame in-memory repository.
 * <p>
 * In general, a triple (Subject, Property, Object) is encoded in the following structure:
 * { "S" : { "P" : [ O ] } }
 * The object of the triple O is represented as a further JSON object with the following keys:
 * <ul>
 * <li>type: one of 'uri', 'literal' or 'bnode' (required and must be lowercase)
 * <li>value: the lexical value of the object (required, full URIs should be used, not qnames)
 * <li>lang: the language of a literal value (optional but if supplied it must not be empty
 * <li>datatype: the datatype URI of the literal value (optional)
 * </ul>
 * The 'lang' and 'datatype' keys should only be used if the value of the 'type' key is "literal".
 * User: Thomas Kurz
 * Date: 17.01.11
 * Time: 13:01
 */
public class RdfJsonParser implements KiWiParser {

	@Inject
    private Logger log;

	private static final String HTTP = "http://";
	private static final String VALUE = "value";
	private static final String TYPE = "type";
	private static final String BNODE = "bnode";
	private static final String URI = "uri";
	private static final String LANG = "lang";
	private static final String DATATYPE = "datatype";

	private static final List<String> MIMETYPES;
	static {
		MIMETYPES = new ArrayList<String>();
		MIMETYPES.add("application/json");
	}

	@Override
	public List<String> getAcceptFormats() {
		return MIMETYPES;
	}

    /**
     * Parse the triple data contained in the reader passed as argument and return a Sesame in-memory repository for
     * further processing.
     *
     * @param data a string containing the triple data in RDF/JSON format
     * @return a Sesame in-memory repository containing the parsed triple data
     * @throws kiwi.core.exception.ParsingException
     *          if the data read from the Reader does not have the right format
     */
    @Override
    public Repository parseTriples(String data) throws ParsingException {
		StringReader r = new StringReader(data);
		return parseTriples(r);
    }

    /**
     * Parse the triple data contained in the reader passed as argument and return a Sesame in-memory repository for
     * further processing.
     *
     * @param reader a Reader from which the triple data in RDF/JSON format
     * @return a Sesame in-memory repository containing the parsed triple data
     * @throws kiwi.core.exception.ParsingException
     *          if the data read from the Reader does not have the right format
     */
    @Override
    public Repository parseTriples(Reader reader) throws ParsingException {

		try {
			ObjectMapper mapper = new ObjectMapper();
			Map<String,Map<String,Set<Map<String,String>>>> subjects = mapper.readValue(reader, new TypeReference<Map<String,Map<String,Set<Map<String,String>>>>>(){});
			return createRepository(subjects);
		} catch (IOException e) {
			log.error("I/O error while trying to read InputStream, this should never happen",e);
		}
		return null;
    }

    /**
     * Parse the triple data contained in the reader passed as argument and return a Sesame in-memory repository for
     * further processing.
     *
     * @param in an InputStream from which the triple data in RDF/JSON format
     * @return a Sesame in-memory repository containing the parsed triple data
     * @throws kiwi.core.exception.ParsingException
     *          if the data read from the Reader does not have the right format
     */
    @Override
    public Repository parseTriples(InputStream in) throws ParsingException {

		try {
			ObjectMapper mapper = new ObjectMapper();
			Map<String,Map<String,Set<Map<String,String>>>> subjects = mapper.readValue(in, new TypeReference<Map<String,Map<String,Set<Map<String,String>>>>>(){});
			return createRepository(subjects);
		} catch (IOException e) {
			log.error("I/O error while trying to read InputStream, this should never happen",e);
		}
		return null;
    }

	private Repository createRepository(Map<String,Map<String,Set<Map<String,String>>>> subjects) throws ParsingException {
		//create in-memory repository
		Repository repository = new SailRepository(new MemoryStore());
        try {
            repository.initialize();
			RepositoryConnection con = repository.getConnection();
   			try {
				con.clear();
      			for(String subjectKey : subjects.keySet() ) {
					//create subject Resource
					Resource subject;
					if(subjectKey.startsWith(HTTP)) {
						subject = new URIImpl(subjectKey);
					} else {
						subject = new BNodeImpl(subjectKey);
					}

					for(String propertyKey : subjects.get(subjectKey).keySet()) {
						//create property URI
						URIImpl property = new URIImpl(propertyKey);

						for(Map<String,String> o : subjects.get(subjectKey).get(propertyKey)) {
							 //create object resources
							Value object;

							if( o.get(TYPE).equals(URI) ) {
								object = new URIImpl(o.get(VALUE));
							} else if( o.get(TYPE).equals(BNODE) ) {
								object = new BNodeImpl(o.get(VALUE));
							} else {
								if( o.get(LANG) != null ) {
							    	object = new LiteralImpl(o.get(VALUE),o.get(LANG));
								} else if( o.get(DATATYPE) != null) {
									object = new LiteralImpl(o.get(VALUE),new URIImpl(o.get(DATATYPE)));
								} else {
									object = new LiteralImpl(o.get(VALUE));
								}
							}
							//add triple
							ValueFactory f = repository.getValueFactory();
							con.add(f.createStatement(subject,property,object));
							//TODO: maybe context for named graphs
						}
					}
				}
				con.commit();
   			}
   			finally {
      			con.close();
   			}
		} catch (RepositoryException e) {
			log.error("Fehler:"+e.getStackTrace().toString());
			throw new ParsingException("Error while parsing input data in RDF/JSON format",e);
		}
		return repository;
	}
}
